Question 167258
R=2B+3
R+B=42
(2B+3)+B=42
3B+3=42
3B=42-3
3B=39
B=39/3
B=13 NUMBER OF BLACK MARBLES.
R=2*13+3
R=26+3
R=29 RED MARBLES.
PROOF:
13+29=42
42=42